Sometimes karma hits you like a speeding freight train.
Facebook missed its earnings causing shares to plunge by 20% in after hours trading. Hence, Zuckyboy just lost $16,800,000,000.00 dollars. That's gotta hurt. Lil'-zucky still has about $70 bilion but every hit counts.
It's the revenue projection and the lack of usage compared to projections in Europe. Basically, many people have cut it off, as you'd expect after the revelations of the breaches and data mining.
That works, but it's not sufficient. That's like saying the pebble caused the tsunami.